FIG. 1 is a networking diagram of the carrier aggregation system, carrier aggregation (CA) of TD-LET (Time Division-Long Time Evolution) cells are mainly based on the bandwidth of 10 M and 20 M, and be conducted in the D, E, and F bands. In a CA system, a plurality of component carriers (CC) simultaneously serving a User Equipment (UE) are classified into Primary Component Carrier (PCC) and Secondary Component Carrier (SCC). The cell corresponding to PCC is called Primary Cell (PCell), PCell will inherit the full function of the service cell of Long Term Evolution (LTE); the cell corresponding to SCC is called Secondary Cell (SCell), and SCell will only bear the function of data transmission. PCell and SCell are viewed from the point of UE, PCell contains downlink (DL) CC and uplink (UL) CC, Scell can contain only DL CC, but it can't contain only UL CC.
As the technology of Long Term Evolution-Advanced (LTE-A) and UE evolve, the LTE-A cell will support transmission mode 9 (TM9), a maximum of 8 ports can be configured for the DL of a cell, which can support up to 8 streams of data transmission for a single user, with transmission rate far exceeding the LTE cell. However, due to the limitation of the UE's transmitting antenna, the CA cell of the present stage mainly considers single/dual-stream transmission, the CA cell does not support CA of 8 DL ports for TD-LTE-A cell using TM9.